During mobile communication, a mobile station device in motion performs a search for a cell (hereinafter, “cell search”) to communicate with a suitable base station device. Based on the result of the cell search, the mobile station device changes the base station device. Patent Document 1 discloses a mobile terminal that changes, based on a moving speed, a time interval at which the cell search is performed.    [Patent Document 1] Japanese Unexamined Patent First Publication No. 2006-246121